Abstract
Water shortage at precarious growth stages diminishes the wheat production, however regulated deficit irrigation and potassium fertilization ameliorate its adversities to a certain extent. A pot experiment was conducted in 2010-11 and 2011-12 growing seasons to assess the effect of regulated deficit irrigation on yield and water use efficiency of wheat under semiarid region of Pakistan. The growing season was divided into six periods viz: germination, jointing, booting, heading, grain filling and maturity stage. Three regulated deficit irrigation levels (no- soil- water- deficit (H: 80-100 % of available water content (AWC)), medium (M) soil water deficit (70 to 80% AWC and severe (L) water deficit (60-70% AWC) were maintained at above mentioned stages in combination with three levels of potassium (0, 200 and 300 kg ha-1 K2O). Soil water contents were measured gravimetrically by weighing pots after 1 to 2 day’s interval throughout the growing season. Potential evapotranspiration (ETp) was calculated using Penman-Montieth model. The actual evapotranspiration (ETa) was calculated using water balance equation and crop coefficient was calculated by dividing the ETa with ETp. The data obtained was analyzed statistically. The results of this study showed that grain yield and water use efficiency in wheat (Sahar-2006) was greatly improved by 23.4 and 15.0% (average of two years) under soil water deficit treatment I3 (MMHMH) with potassium (K2O applied at 300 kg ha-1 ) as compared to regulated deficit treatment I1 (HMLML) in combination without potassium (K2O applied at 0 kg ha-1 ). The optimum total irrigation water of 242.9 mm was distributed as 13.7 mm during germination stage, 22.15 mm during jointing, 21.10 mm during booting, 69.95 mm during heading, 58.9 mm during grain filling and 57.05 mm during maturity to fulfill the need of actual evapotranspiration which was required to produce the above mentioned increase in grain yield and other parameters. Root length and mass density were also increased by 35.9 and 35.6% in pot receiving I3 (MMHMH) in combination with K2 over I1 (HMLML) in combination with K0. K nutrition helped in mitigating the negative effects of water stress due to well developed root system and accelerated the maximum water uptake and improved water use efficiency
Muhammad Imran, Anwar-Ul-Hassan, Muhammad Iqbal, Ehsan Ullah, Jirka Šimunek. (2015) Assessment of actual evapotranspiration and yield of wheat under different irrigation regimes with potassium application, The Journal Soil & Environment , Volume 34, Issue 2.
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